My understanding of this building, admittedly as someone not part of the BU campus community, is that a) the terraces are mostly actually a green roof with very limited terrace bits with seating and b) the portion that are meant to be more "public" for general student use is the podium section, which contains the classrooms, and that the tower section is occupied by faculty offices and institutional research / departmental space - more grad student workstations than lecture halls. If grad students count as faculty, I can generally understand the restrictions from a purely a " all locked doors up here are staff only, and we're working but we can give you a quick tour for the view." I've always thought of them as being a workplace amenity.
I went to UMass Amherst, which culturally seemed to be "BU in Western Mass," Many of the buildings there were built with balconies, namely the The Southwest Towers & Low Rises, and O Hill. My God the lore... I realize that this building isn't a dorm, but inebriated college students will do what they will anywhere they have access.
It could be as innocent as somehow getting a cow onto the 20th floor balcony, or in the form they existed in my time there, *several* students fell/jumped every year from the O-Hill balconies, not to mention suicide Sylvan or the historical falls from the SWest Towers or the student who died elevator surfing in one. A 20 story fall is a very hard lesson to learn, and I begin to understand the urge on the part of the administration to keep the undergrads away.
